Two-nucleon multiplets near mass A = 88 and the implication for the residual nucleon-nucleon interaction

The low excitation energy spectroscopy of 86Sr, 88Sr, 89Sr, 86Rb, and 87Rb nuclear systems was studied via one-nucleon transfer reactions. The strontium isotopes, 87Sr and 88Sr, were used as targets in this study. Spectroscopic strengths were extracted from the measured transfer reaction cross sections and the distorted wave Born approximation (DWBA) analysis. Efforts have been made to accomplish a complete detection of spectroscopic strengths through the excitation energy region where levels can be resolved and identified. A shell model sum rule analysis is then made. Diagonal matrix elements for the effective two-nucleon interaction were deduced from empirical energy centroid. Matrix elements normalized by their empirical monopole energy was plotted against the semiclassical angle between two spins. They were compared with various analytical function forms of the effective two-nucleon interaction depending on their spins, isospins, and parities